Double-acting two-stroke internal combustion engine



June 14, 1932.

M. TRECHSEL DOUBLE ACTING TWO-STROKE INTERNAL COMBUSTION ENGINE FiledSept. 19, 1929 0- Arid/Fill Patented ti e 34, rear UNITED STATES rA'rsNr MAX ranonsnn, or wmrnnrnun, swniznanann, ASSIGNDB re rerun: on serene rnnnns socrn'rn ANONYME, or-wmrnn'rnu'n, swmnnnanrn DOUBLE-ACTING TWO-STROKE INTERNAL CGI'EEUSI'IGN ENGINE Application filed September 19, 1929, Serial No.

This invention relates to double-acting two-stroke internal combustion engines and in particular to engines in which both the cylinder body and its liner are transversely divided and furnished with an intermediate connecting member.

In known double-acting two-stroke internal combustion engines constructed in this manner the working forces occurring in the axial direction are transmitted to the cylinder cover through the parts of the cylinder liner, whereby undue stresses are imposed on the engine, and particularly on the parts of the cylinder liner, which often give rise to disturbances in workin Further in engines of this type difficulties arise in cleaning and repairing owing to the necessity for undoing pipe connections in order to withdraw the parts of the divided cylinder body from one another.

The object of the present invention is to obviate these disadvantages, and to this end the arrangement is such that the axial working forces set up in each half cylinder taken as a whole are transmitted through the cylinder body to the intermediate member or to the frame, the two halves of the cylinder liner abutting against one another for centering purposes with axial play but without packing in the neighborhood of the ports, whereby the half cylinders are left free of air inlet or exhaust pipe connections.

A convenient construction of vertical double-acting internal combustion engines ac cording to the invention is illustrated by way of example in the accompanying drawing, in which Figure 1 is a longitudinal section through the cylinder.

' Fig. 2 shows the upper half of the cylinder of a machine in accordance with Fig. 1, when removed.

Fig. 3 shows the lower half of the cylinder of an internal combustion engine, in accordance with Fig. 1, and in the broken line, the piston in its extreme (highest) osition.

Fig. 4 shows the bayonet cap trom above.

In the construction illustrated, the piston 1 mounted on the piston rod 2 is dis osed in a cylinder comprising a lower cy inder 393,688, and in Switzerland Gctober 30, 1928.

head 3, an upper cylinder head l, and a liner divided into upper and lower halves 5 and 6. The upper cylinder body 7 and the lower cylinder body 8 are held together by means of the intermediate member 9 and bolts 2%. Bolts 23 pass through the upper cylinder body 7 and enter the cylinder liner 5 and secure the cylinder liner to the cylinder body.

In a cover 20 in the upper cylinder head is inserted a valve casing 10, containing for example the injection and starting valves. The injection valves for the lower half of the cylinder are omitted for simplicity. The lower cylinder head is provided with a stutting box 11 for the piston. Cooling water chambers are provided at 21 in the cover, at 12 in the upper cylinder half and at 13 in the lower cylinder half. scavenging air enters through the ports 14, and charging air through the ports 15, whilst the exhaust gases are led away through the ports 16. The upper liner, and therefore also the upper cylinder half, is centred by means of the circular guide 1? on the lower liner.

The scavenging and charging are efiected in the well-irnown manner. At the end of the expansion stroke the piston first uncovers the charging air ports 15, the exhaust gases being prevented from escaping into the chargin air vessel by means ofvalves (not shown}. After uncovering the ports 15, the piston opens the exhaust ports 16 to equalize the pressure in the working cylinder and then the scavenging air ports 14 whereupon the scavenging air enters the cylinder and drives the exhaust gases in the cylinder out through the exhaustports.

@n its return stroke the piston first closes the scavenging ports 14; and then the exhaust ports 16. Since the charging air pressure is greater than that in the cylinder, the charging air inlet valves open and additional air enters the working space until the piston closes the ports 15, whereupon air compres that the packing joints for the water chambers 12 and 13 with the exception of the pipe connection or the cooling water inlet and outlet) as well as the scavenging and exhaust pipe connections do not have to be detached when the up r cylinder half is removed. The two 0 linder halves are centred by means of the liners, thus giving greater accuracy in centering than could be obtained by means of the cylinder bodies or like parts of large diameter whose manufacture and expansion during running might give rise to centering errors.

The ortion of the lower cylinder half containing the connections for the scavenging air and exhaust pipes is flared at the top in such a way that when the upper cylinder half is removed there is sufiicient space between the piston, when in its uppermost position, and the middle portion carryino the connections for the scavenging air an exhaust orts for the piston to be inspected right own to the bottom. By the aid of mirrors even the under surface of the piston and the piston rod can be seen. In this position the piston can be completely cleaned and all the piston rings can be replaced. It should be noted that this is possible without disturbin the crosshead or the connecting rod.

Vhen replacing the upper half of the cylinder one joint only has to be remade, namely between the upper cylinder body 7 and the middle member 9 at the joint 18. This joint is readily accessible from outside and has only to withstand pressures not exceed ing the scavenging air pressure, i. e. excess pressures of at most some 0.2 to 0.3 atmospheres.

If the lower liner needs renewing, it can be at once withdrawn, after removal of the upper cylinder half and the piston, as soon as the bayonet joint 19 of the lower cylinder cover has been unfastened. This is accomplished, referring to Fig. 4, by rotating the ring 19 in a manner such that the upper screw 30 which is on the axis B when the bayonet lock is closed, enters the axis A; after which 0 eration the ring 19 can be direc'tly remove in a downward direction. In Fig. 4 the circles 30 indicate screws. The latter appear as circles, because the six-edge screw head is on the reverse of the ring 19. The rin 19 is a portion of the bayonet look as can seen in Fig. 4; the other portion is on the lower cylinder head 22. In this case also in contradistinction to the known constructions the connections for the scavenging air and exhaust pipes do not have to be broken and the lower cylinder half and the intermediate member do not need to be moved.

The lower cover 22 carrying the stufiing box may be withdrawn upwardly either alone or together with the lower liner. The lower, as well as the upper cylinder cover are so constructed that they transfer the working forces acting on them directly to the cylinder body without the aid of tension bolts. In this way the forces acting on the cylinder covers are taken up with a high degree of safety, and moreover the dimensions of the connecting bolts 23 can be reduced.

\Vith the arrangement described the height required for dismantling the piston and piston rod is considerably less than that necessary with previously known constructions. In order to effect this dismantling laterally the lower end of the piston rod need not be raised above the cover bolts, but only above the centre member. The height of the building necessary to house the engine may therefore be reduced to the greatest possible extent. The whole arrangement permits the time and work required for the regular examination and overhaul of the engine to be considerably reduced.

The intermediate member 9 may, if desired, be cast in one piece with the lower cylinder body instead of being separate therefrom as shown.

The invention may also be used with horizontal engines, in which case the arrangement above described is applicable, reference to the lower cylinder half being taken to apply to the cylinder half nearer the crank and those to the upper cylinder half to apply to the cylinder half remote from the crank.

I claim 1. In a double-acting two-stroke internal combustion engine, a transversely divided cylinder body, abutting cylinder liners disposed in axial alignment having scavenging air ports, charging air ports and exhaust air ports adjacent the line of abutment 3 of the liners, and an intermediate connecting member disposed between said divided cylinder body, said intermediate member having passages therein connecting with the scavenging air ports, the charging air ports and the exhaust air ports.

2. An apparatus according to claim 1,- wherein the portions of the cylinder liner' and the cylinder body on the same side of the line of division are secured together.

3. An apparatus according to claim 1, including scavenging air, charging air and exhaust conduits connected to the intermediate connecting member.

In testimony whereof I have afiixed my signature.

MAX TRECHSEL. 

